Use the following code for the navbar template edit instead of the one he provided. He renamed his handler and ajax call functions but didnt update the instructions for the template edit to reflect it.
Oops forgot to paste the code
Code:
<strong><phrase 1="$bbuserinfo[username]" 2="member.php?$session[sessionurl]u=$bbuserinfo[userid]">$vbphrase[welcome_x_link_y]</phrase></strong> <if condition="$showinvisiblemode"><img class="inlineimg" src="$stylevar[imgdir_statusicon]/<if condition="!$invisiblemode">in</if>visible.gif" alt="$vbphrase[ajax_invisible_mode]" onclick="requestSwitchData('index.php?{$session[sessionurl]}do=doinvisiblemode&userid={$invisiblemodeuser}','parseSwitch',this)" /></if><br />